Re: comments re draft version 2.0

> The capability seems to be present.

Yes.  I was writing about using TeX-like author markup as close as
possible to tradition to create content-sound SGML suitable for
translation to MathML.

I had suggested that given (with simplified typing)

> > \declaremathsymbol{D}{operator}
> > \declaremathsymbol{y}{function}

the expression  D^2 y  would be adequate author markup.

You wrote:

>       D^2 ( y )  could equally  well mean   D(y) * D(y)

While both of these two expressions are consistent with the types, the
second is more naturally indicated with (D y)^2, which requires parentheses
in order to distinguish it from D (y^2), while parentheses in the
expression  D^2 (y) do not serve to distinguish it from  D^2 y .

If a parser were to infer D(y)*D(y) from D^2 y , then wouldn't it be
via an earlier inference of (D y)^2 from D^2 y ?  But doesn't
convention dictate that exponents bind more tightly than
juxtapositions?  Aside from that one reaches (D y)^2 only after
reversing the order of '2' and 'y' in the parse.  (The interpretation
D^(2y) is eliminated out by the TeX rule that a superscript of more
than two markup characters must be braced and also, without more
context, precluded by the types.)

                                    -- Bill